Researchers from Canada reported the case of a neonatal-onset carnitine palmitoyltransferase II (CPT II) deficiency, a type of long-chain fatty acid oxidation disorder (LCFAOD), identified through newborn screening using tandem mass spectrometry.

This led to avoidance of metabolic decompensation, early treatment, and a better clinical outcome. 

“This experience illustrates the importance of newborn screening for CPT II deficiency and demonstrates why reconsideration should be taken to add this disease as a primary newborn screening target,” wrote the authors of the study, which was published in the International Journal of Neonatal Screening.

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Read more about LCFAOD diagnosis

In Canada, the Maritime Newborn Screening Program began screening for CPT II deficiency in 2005. Since then, the program screened more than 220,000 newborns and identified 1 positive case, which is the one that researchers report in the present study. It is that of a female infant of Caucasian descent born at 40 weeks and 3 days weighing 3,374 kg.  

“Newborn screening for CPT II deficiency is highly sensitive and specific with no false positives identified,” the researchers said.

CPT II is 1 of 6 types of LCFAOD where the CPT2 gene, which encodes the CPT II enzyme, is mutated. This results in the activity of the enzyme being reduced. The role of this enzyme is to remove the carnitine molecule that was added to long-chain fatty acids so they can be transported into the mitochondria.

The removal of the carnitine molecule by CPT II ensures long-chain fatty acids are ready to be metabolized inside the mitochondria. When there is not enough functional CPT II enzyme, carnitine cannot be removed efficiently and long-chain fatty acids cannot be metabolized. Instead, they accumulate becoming toxic and causing damage. There is also a reduction in energy production.

Following a strict nutritional plan and consuming a diet low in long-chain fatty acids with the supplementation of medium-chain triglycerides can help manage the disease and reduce the detrimental effects of long-chain fatty acid accumulation. It is therefore of great importance to diagnose the disease early, emphasizing the importance of newborn screening.


Mador-House R, Liu Z, Dyack S. Detection of early onset carnitine palmitoyltransferase II deficiency by newborn screening: should CPT II deficiency be a primary disease target? Int J Neonatal Screen. 2021;7(3):55. doi:10.3390/ijns7030055